Mailing List Archive

[PATCH gnupg] sm: Support generation of card-based ed25519 CSR.
Hi,

On Thu, 14 Feb 2019 23:19:52 +0000, Damien Goutte-Gattat wrote:
> > (1) There are three cases; RSA, ECDSA, and EdDSA. It's good that we
> > can support all.
>
> Agreed. I have another patch in the works to add support for EdDSA.

Here is the patch to add EdDSA support when generating a CSR from a
token-based key.

What is still missing for this to work is support from Libksba, which
currently generates both an incorrect SPKI and an incorrect signature
value for EdDSA-based CSRs.


-- >8 --
Subject: sm: Support generation of card-based ed25519 CSR.

* sm/call-agent.c (gpgsm_scd_pksign): Allow SHA512. Create proper
S-expression for EdDSA signature.
* sm/certreqgen.c (create_request): Force use of SHA512 when
using a ed25519 key.
* sm/misc.c (transform_sigval): Insert OID for ed25519.

GnuPG-bug-id: 4013
Signed-off-by: Damien Goutte-Gattat <dgouttegattat@incenp.org>
---
sm/call-agent.c | 7 +++++++
sm/certreqgen.c | 6 ++++--
sm/misc.c | 10 ++++++++--
3 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/sm/call-agent.c b/sm/call-agent.c
index 6ac715fab..4f2b83f56 100644
--- a/sm/call-agent.c
+++ b/sm/call-agent.c
@@ -354,6 +354,7 @@ gpgsm_scd_pksign (ctrl_t ctrl, const char *keyid, const char *desc,
case GCRY_MD_RMD160:hashopt = "--hash=rmd160"; break;
case GCRY_MD_MD5: hashopt = "--hash=md5"; break;
case GCRY_MD_SHA256:hashopt = "--hash=sha256"; break;
+ case GCRY_MD_SHA512:hashopt = "--hash=sha512"; break;
default:
return gpg_error (GPG_ERR_DIGEST_ALGO);
}
@@ -417,6 +418,12 @@ gpgsm_scd_pksign (ctrl_t ctrl, const char *keyid, const char *desc,
sigbuflen/2, sigbuf + sigbuflen/2);
break;

+ case GCRY_PK_EDDSA:
+ rc = gcry_sexp_build (&sig, NULL, "(sig-val(eddsa(r%b)(s%b)))",
+ sigbuflen/2, sigbuf,
+ sigbuflen/2, sigbuf + sigbuflen/2);
+ break;
+
default:
rc = gpg_error (GPG_ERR_WRONG_PUBKEY_ALGO);
break;
diff --git a/sm/certreqgen.c b/sm/certreqgen.c
index 1d610c1bb..01fba30f5 100644
--- a/sm/certreqgen.c
+++ b/sm/certreqgen.c
@@ -807,8 +807,10 @@ create_request (ctrl_t ctrl,
if (err)
return err;

- string = get_parameter_value (para, pHASHALGO, 0);
- if (string)
+ len = gcry_sexp_canon_len (public, 0, NULL, NULL);
+ if (get_pk_algo_from_canon_sexp (public, len) == GCRY_PK_EDDSA)
+ mdalgo = GCRY_MD_SHA512;
+ else if ((string = get_parameter_value (para, pHASHALGO, 0)))
mdalgo = gcry_md_map_name (string);
else
mdalgo = GCRY_MD_SHA256;
diff --git a/sm/misc.c b/sm/misc.c
index 9bf528513..4672f269e 100644
--- a/sm/misc.c
+++ b/sm/misc.c
@@ -146,6 +146,8 @@ transform_sigval (const unsigned char *sigval, size_t sigvallen, int mdalgo,
pkalgo = GCRY_PK_RSA;
else if (toklen == 5 && !memcmp ("ecdsa", tok, 5))
pkalgo = GCRY_PK_ECC;
+ else if (toklen == 5 && !memcmp ("eddsa", tok, 5))
+ pkalgo = GCRY_PK_EDDSA;
else
return gpg_error (GPG_ERR_WRONG_PUBKEY_ALGO);

@@ -170,7 +172,7 @@ transform_sigval (const unsigned char *sigval, size_t sigvallen, int mdalgo,
mpi = &rsa_s;
mpi_len = &rsa_s_len;
}
- else if (pkalgo == GCRY_PK_ECC)
+ else if (pkalgo == GCRY_PK_ECC || pkalgo == GCRY_PK_EDDSA)
{
mpi = &ecc_s;
mpi_len = &ecc_s_len;
@@ -236,6 +238,10 @@ transform_sigval (const unsigned char *sigval, size_t sigvallen, int mdalgo,
oid = "1.2.840.10045.4.3.4"; /* ecdsa-with-sha512 */
break;

+ case GCRY_MD_SHA512 | (GCRY_PK_EDDSA << 8):
+ oid = "1.3.101.112"; /* ed25519 */
+ break;
+
default:
return gpg_error (GPG_ERR_DIGEST_ALGO);
}
@@ -245,7 +251,7 @@ transform_sigval (const unsigned char *sigval, size_t sigvallen, int mdalgo,
else if (pkalgo == GCRY_PK_RSA)
err = gcry_sexp_build (&sexp, NULL, "(sig-val(%s(s%b)))", oid,
(int)rsa_s_len, rsa_s);
- else if (pkalgo == GCRY_PK_ECC)
+ else if (pkalgo == GCRY_PK_ECC || pkalgo == GCRY_PK_EDDSA)
err = gcry_sexp_build (&sexp, NULL, "(sig-val(%s(r%b)(s%b)))", oid,
(int)ecc_r_len, ecc_r, (int)ecc_s_len, ecc_s);
if (err)
--
2.14.5


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Re: [PATCH gnupg] sm: Support generation of card-based ed25519 CSR. [ In reply to ]
Damien Goutte-Gattat via Gnupg-devel <gnupg-devel@gnupg.org> wrote:
> Here is the patch to add EdDSA support when generating a CSR from a
> token-based key.

Thanks. Applied and pushed.
--

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